Impacts of Spring-interseeded Cover Crops on Late-emerging Weed Suppression and Ground Cover in Corn (Zea mays L.) Production Systems

Any alternative crop management strategy will only be adopted by growers if yield is not negatively impacted, fits within a current management practice, is easily implementable with minimal cost, or provides other beneficial features such as weed control or suppression. Corn production that incorporates a cover crop as an alternative weed control strategy and ground cover may support a sustainable system that is less dependent on herbicidal weed control. In addition, the cover crop may be used as a fall forage, act as a slow release fertilizer source the following year, and provide ground cover to reduce soil erosion. In South Dakota, cover crop establishment cannot occur after corn harvest, as the growing season is too short, cold, and often dry. Therefore, interseeding cover crops into standing corn has the potential to establish, suppress late-emerging weeds, and provide late season ground cover. The purpose of this research was to examine if a cover crop mixture could be established in a standing corn crop at V5 growth stage, suppress weeds, and provide ground cover after corn harvest without negatively impacting corn yield. Crimson clover (Trifolium incarnatum), winter wheat (Triticum aestivum) and lentil (Lens culinaris) were planted using broadcast or drill methods, as a mixture at a rate of 5.4, 8.9, and 9.8 kg ha-1, respectively, into V5 corn in field studies from 2010 – 2012. In 2010 - 12, the mix was planted at summit (SMT) and toeslope (TSP) locations in corn fields near Andover, SD. In 2011 – 12 the mix also was planted at SMT and TSP locations near Trail City, and in a flat field near Aurora, SD. Corn and cover crop and weed biomass were collected each fall. Cover crops emerged about 14 d (days) after planting. Winter wheat and crimson clover were the only species that survived until corn harvest. The drill interseeding method had 76% more cover crop biomass than the broadcast method. Cover crops drill seeded reduced grass weed biomass by 38%. Regardless of seeding method, cover crops had no impact on corn grain yield. These results indicate that cover crops could be established in standing corn with no adverse yield impact. These crops provided ground cover during and after the corn growing season and suppressed late-emerging grass weed growth. Therefore, interseeding this cover crop mix into standing corn may be a feasible alternative management strategy for getting a cover crop established, as SD weather is too cold, dry, and season too short for after harvest planting

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Corn Yield Is Not Reduced by Mid-Season Establishment of Cover Crops in Northern Great Plains Environments

In northern climates, establishment of fall cover crops after corn or soybean harvest is difficult due to cold and dry conditions. This study examined an alternative option: in-season cover crop seeding, timed for plants to emerge just following the critical weed-free period of corn (Zea mays L.) to allow establishment and growth without compromising yield. Crimson clover (Trifolium incarnatum L.), lentil (Lens culinaris Medik.), and winter wheat (Triticum aestivum L.) seed was blended and either drill (DRL) or broadcast (BRD) seeded into corn at the five-leaf (V5; late June) growth stage at three South Dakota sites (7 site years) and at V3 at one site in 2 years. Visual observations in mid-July verified establishment, and aboveground live (e.g., green) biomass was quantified at about R4 (soft dough), prior to corn grain harvest. Cover crop establishment and growth were superior with DRL seeding, which had rapid establishment and more aboveground biomass compared with BRD seeding. Although the total biomass in the V3 and V5 DRL treatments was similar, corn yield was reduced 10% in the V3 seeded plots but was unaffected by V5 seeding. Soil microbial communities were similar to the no-cover-crop control. Our results suggest that cover crops can be established successfully in standing corn at the V5 growth stage without compromising grain yield

Winter Cover Crops Impact on Corn Production in Semiarid Regions

Winter cover crops have produced mixed impacts on crop yields in frigid semiarid environments. Our objective was to determine the influence of winter cover crops and landscape positions on corn (Zea mays L.) yield losses due to water and N stress, soil biology, and gene expression. Following wheat (Triticum aestivum L.), cover crop mixtures were drill seeded into three no-till fields. In the following spring, four N fertilizer rates were applied and corn was no-till seeded. The cover crop had fundamentally different impacts on corn yields at Trail City and Andover in 2011. Both sites were water stressed and responded to N fertilizer; however, at Andover 2011 the cover crop reduced corn yields, while at Trail City 2011 the cover crop did not impact yields. The yield reduction at Andover 2011 was attributed to high cover crop production ( \u3e2000 kg ha–1), which reduced soil water 15% in the 30- to 60-cm soil depth in November 2010, and in the following growing season increased corn yield loss due to water stress from 1610 to 2950 kg grain ha–1. Associated with the yield reduction was down expression of two mineral nutrient genes (NCBI, AF325723.1 and APO05869.3) and one gene associated with energy processing (AF325723.1). The cover crops reduced the relative amount of soil NO3 at four of the six landscape positions and increased the relative bacteria/fungi ratio in 2011. These findings indicate that cover crops after winter wheat can be an important mechanism for scavenging N in semiarid frigid environments; however, adopting techniques that generate high cover crop yields can adversely influence the following cash cro

Geoeconomic variations in epidemiology, ventilation management, and outcomes in invasively ventilated intensive care unit patients without acute respiratory distress syndrome: a pooled analysis of four observational studies

Background: Geoeconomic variations in epidemiology, the practice of ventilation, and outcome in invasively ventilated intensive care unit (ICU) patients without acute respiratory distress syndrome (ARDS) remain unexplored. In this analysis we aim to address these gaps using individual patient data of four large observational studies. Methods: In this pooled analysis we harmonised individual patient data from the ERICC, LUNG SAFE, PRoVENT, and PRoVENT-iMiC prospective observational studies, which were conducted from June, 2011, to December, 2018, in 534 ICUs in 54 countries. We used the 2016 World Bank classification to define two geoeconomic regions: middle-income countries (MICs) and high-income countries (HICs). ARDS was defined according to the Berlin criteria. Descriptive statistics were used to compare patients in MICs versus HICs. The primary outcome was the use of low tidal volume ventilation (LTVV) for the first 3 days of mechanical ventilation. Secondary outcomes were key ventilation parameters (tidal volume size, positive end-expiratory pressure, fraction of inspired oxygen, peak pressure, plateau pressure, driving pressure, and respiratory rate), patient characteristics, the risk for and actual development of acute respiratory distress syndrome after the first day of ventilation, duration of ventilation, ICU length of stay, and ICU mortality. Findings: Of the 7608 patients included in the original studies, this analysis included 3852 patients without ARDS, of whom 2345 were from MICs and 1507 were from HICs. Patients in MICs were younger, shorter and with a slightly lower body-mass index, more often had diabetes and active cancer, but less often chronic obstructive pulmonary disease and heart failure than patients from HICs. Sequential organ failure assessment scores were similar in MICs and HICs. Use of LTVV in MICs and HICs was comparable (42·4% vs 44·2%; absolute difference -1·69 [-9·58 to 6·11] p=0·67; data available in 3174 [82%] of 3852 patients). The median applied positive end expiratory pressure was lower in MICs than in HICs (5 [IQR 5-8] vs 6 [5-8] cm H2O; p=0·0011). ICU mortality was higher in MICs than in HICs (30·5% vs 19·9%; p=0·0004; adjusted effect 16·41% [95% CI 9·52-23·52]; p<0·0001) and was inversely associated with gross domestic product (adjusted odds ratio for a US$10 000 increase per capita 0·80 [95% CI 0·75-0·86]; p<0·0001). Interpretation: Despite similar disease severity and ventilation management, ICU mortality in patients without ARDS is higher in MICs than in HICs, with a strong association with country-level economic status

The value of open-source clinical science in pandemic response: lessons from ISARIC

International audienc